Aircraft



G. MINELLI March 28, 1939.

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AIRCRAFT Filed July 2, 1937 1 6 Sheets-Sheet 2 -55 use amfle ZZZ (5. MINELLI March 28, 1939.

AIRCRAFT Filed July 2, 1937 6 Sheets-Sheet 3 awe/whom M72611 1 Y @L Sxwww 5 z'uaeppe G. MINELL! AIRCRAFT Filed July 2, 1957 6 Sheets-Sheet 4 & Giusepp [Mine]! March 28, 1939.

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AIRCRAFT Filed July 2, 1937 6 Sheets-Sheet 6 fin/vented aiufieivf ZZZ Patented Ma. 23,1939

UNITED STATES PATENT OFFICE amoam Giuseppe Minelli, Dawson, N. Mex. Application July 2, 1937, Serial No. 151,728

Claims.

An object of the invention is to provide means 5 to be installed on aircraft, for instance, an airplane, which will effectively and emciently function to control both horizontal and vertical avigation of the airplane, without human supervision, in a given direction and at an initially determined or given altitude.

Another object of the invention has to do with the provision of a flight control mechanism of the kind mentioned and which is comparatively simple and easy to adjust," both with regard to flight altitude and direction, and entirely automatic in operation to compensate for adverse flight conditions, maintaining the craft. on its course until and after an objective is reached.

A further object of the invention resides in the provision of automatic control mechanism for the aileron, elevator and rudder controls of aircraft, and which are comparatively simple in construction, adjustment and operation, and capable of being installed on standard types of aircraft, without necessitating serious or undue changes in the usual construction and exterior and interior arrangements of such craft.

Yet another objectof the invention is to provide independent electrically "operated control mechanism for the elevator and rudder controls of the aircraft, including automatic circuit switching devices therefor, an altimeter controlled switch for the mechanism toautomatically actuate the elevators, and a compass controlled switch for the mechanism to automatically actuate the rudder, the switching devices each adjustable to operate correspondingly with predetermined settings of the altimeter and compass to maintain the aircraft on itsv flight course.

Still another objectlof-the invention has to do with the provisions of automatic gravity controls I which cooperate with-and aid in'the functions of the automatic electrically operated control mechanisms for greater accuracy and precision in the I setting of the craft controls for smooth and positive maneuvering of the craft to keep it on its course}:

With these and other objects of equal importance in view, the invention resides in the certain new and useful combination, construction and arrangement of parts, circuits and instrumentalities as will be hereinafter more fully described, set forth in the appended claims, and illustrated in the accompanying drawings, in which:

Figure 1 is a top plan view, partly in section. of a conventional type of airplane equipped with the automatic con-devices and mechanisms, in accordance with the invention;

Figure 2 is a side elevation of the empennage or tail assembly 01' the airplane;

Figure 3 is an enlarged detail, in side elevation, of a gravity or pendulum control device for each of the ailerons;

Figure 4 is an enlarged front side elevation, partly in section, of the automatic altimeter controlled switching device for controlling the elevators;

Figure 5 is a vertical section taken on the line 55 of Figure 4;

Figure 6 is a horizontal section taken on the line 6-6 of Figure 4;

Figure 7 is a vertical section taken on the line of Figure 5;

Figure 8 is a fragmentary vertical section taken on the line 88 of Figure 5;

Figure 9 is a side elevation, partly in section, of the automatic compass controlled switch device for controlling the rudder;

Figure 10 is a horizontal section taken on the line Ill-i0 of Figure 9;

Figure 11 is an enlarged, fragmentary, vertical section taken on the line "-4 I of Figure 1, and showing a part of the rudder control mechanism in side elevation;

Figure 12 is a detail, in front elevation, of the gravity or pendulum control device as shown in Figure 3;

Figure 13 is a side elevation, partly in section, of an automatic throttle control for the fuel supply to the engine;

Figure 14 is a horizontal section taken on the line I4-l4 of Figure 13;

Figure 15 is a diagram of the electrical circuit connections for the altitude-elevator control mechanism;

Figure 16 is a diagram oi-the electrical circuit connections for the direction-rudder control mechanism;

Figure 17 is a vertical sectional view taken on line |'|-|1 of Figure 11;

Figure 18 is a front elevational view of the switch, and

Figure 19 is a diagrammatic view of a wiring arrangement for the elevator control mechanism.

Referring to the drawings, wherein like charactors of reference denote corresponding parts throughout the several views, and more particularly to Figures 1, 2 and 11, the airplane shown is of a standard monoplane type and comprises generally a fuselage 2| wing panels or aerofoils 22 equipped with usual ailerons 23 at the tips of their trailing edges; and horizontal and vertical stabilizers 24 and 25 respectively provided with elevators 26 and a rudder 21 hinged to their trailing edges. A propeller 23 is driven from an engine 23 mounted within the nose of the fuselage. A usual fuel supply (not shown) and ignition system (also not shown) is provided for the operation of the engine 23.

In carrying out the objects and purposes of the instant invention, an automatic gravity control device is provided for each of the ailerons 23 and it is comprised in a weighted arm or pendulum 30 pivotally mounted, as at 3|, on the leading edge of an aerofoil 22 in proximity to its outer end. The direction of swing of the pendulum 30 is parallel to the said leading edge, 1. e., at right angles to the flight path of the craft. The upper pivoted end of the pendulum 30 is connected by a pair of wires 32, one wire end at a point above and an end of the other wire at a point below the pivot 3| and the opposite ends thereof respectively to the upper and lower sides of an aileron 23 substantially at its center; the points of connection of the wire ends to both the pendulum and the aileron being such that the wires are supported free from contact with the opposed surfaces of the aerofoil. From the points of connection with the aileron, the wires 32 extend forwardly above and below the aerofoil sur faces and pass angularly about grooved guide rollers 33 mounted on the upper and lower sides of the leading edge of the aerofoil and outwardly in slightly spaced relation to the latter to the points of connection with the pendulum 30. To equalize the tension on the wires 32 and compensate for variations therein as may be required from time to time, a turnbuckle 34 is spliced into each wire to that end. The two controls thus provided, while independent one of the other and normally functioning to hold the ailerons 23 at neutral, operate simultaneously to shift them as required to maintain the craft in balance or equilibrium at all times during flight.

Similarly, an automatic gravity control or joystick is provided for the elevators 26 and, as shown, it is comprised in a single weighted arm or pendulum 35 which depends through a slotted opening 35 in the bottom or floor of the fuselage 2 I This opening 36 is disposed in the plane of the longitudinal center of the fuselage bottom or fioor and at a point that approximates the usual position of the control stick of a pilot operated craft. The pendulum 35 is suspended through the opening 36 from a transverse pivot 31 secured in a frame-work 33 which functions as a reinforcement for the fuselage bottom or floor about the opening. In this instance, the direction of swing of the pendulum is in a plane parallel to the flight path and at right angles to that of each of the pendulums 30. Extending between points of connection with the upper pivoted end of the pendulum 35 and the elevators 26 are pairs of wires 35, one pair for control of the left elevator and the other of the right elevator. The wires of each pair have their forwardly directed ends commonly connected to the pendulum 35 at a point below the pivot 31 and each of their rearwardly directed ends to the usual horn on the lower side of an elevator, while the wires of the other pair have their forwardly directed ends similarly connected to the pendulum 35 at a point above the pivot 31 and each of their opposite ends to the horn on the upper side of an elevator. From the points of connection with the pendulum 35, each of the wires 39 connected to the lower sides of the elevators 26 pass outwardly of an opening 45 in a side wall of the fuselage 2| and over a grooved guide roller 4| mounted within the opening, while the other of the wires 39 pass from their points of connection with the pendulum 35- to the upper sides of the elevators 26 exteriorly of the fuselage 2| and over grooved guide rollers 4| mounted on the bottom of the latter in line with the rollers 4|. Here also, turnbuckles 42 are spliced in the several wires 39 for equalizing the tension thereof. The pendulum 36 and the control wires 39 thus provided function to sustain the elevators 26 normally at neutral and to return them to such positions following each positive actuation thereof during vertical avigation.

For the desired pilotless operation of the craft in vertical and horizontal avigation, the elevators 26, in addition to the aforesaid gravity con trol, and the rudder 21, are to be electrically actuated automatically respectively by altimeter and compass control devices which are arranged for selective setting to predetermined altitude and direction of flight. These control devices and their related instrumentalities, including the circuit connections therefor, are housed within the fuselage 2| in a suitable manner, both with regard to accessibility and convenience for inspection and maintenance.

The actuating mechanism-for the elevators 25 is comprised in an electric motor 43 having a gear 44 in mesh with a rack bar 45 supported for longitudinal movements on a pair of rollers 45 journalled in a bracket 41 rising from a base 46 on which the motor 43 is also mounted. This base 43 is secured in place on the bottom or floor of the fuselage 2| rearwardly of the pendulum 35 and in a position that one end of the rack bar 45 is conected by a pitman 49 to the pendulum 35, one end of the pitman being pivoted, as at 55, to the rack bar 45 and its other end, as at 5|, to the extreme upper end of the pendulum. Reversed directional motion of the motor 43 will actuate the rack bar 41 to swing the pendulum 35 on its pivot 31 and thereby move the elevators 26 as may be required from time to time during craft flight. When the motor 43 comes to rest, the pendulum 35 immediately functions to return the elevators 26 to neutral, as before stated.

The operation of the motor 43 is automatically regulated from a switching device under the constant control of an altimeter 52 which is of standard construction but especially mounted for required cooperation with the switching device. As best shown in Figures 4 to 8, inclusive, the altimeter 52 is mounted within an annular frame 53 for angular adjustment therein, a set screw or the like 54 being provided to hold it in any selected set position. The frame 53 is supported on radial members 55 from one side of a vertical member or post 56 rising from a base 51 secured transversely within and upon the bottom or floor of the fuselage 2|. The dial face 52 of the altimeter 52 is unenclosed for the cooperation of its index or pointer 52" with a fixed contact pin 58 and a movable contact pin 59. This movable contact pin 59 projects toward the dial face 52' from one end of an insulated member 50 slidably mounted in an opening 6| in the post 55. The member 60 has its other end pivoted, as at 62, to the upper end of an arm 63 which is pivoted toward its lower end, as at 64, to the side of the post opposite the side on which the altimeter frame 53 is supported. This arm 88 is actuated to move the pin contact .58 into and out of the path of the index or pointer 52" ofthe insulated slide member 88 partially outward of the opening 8| to remove the pin contact 58 from the path of the index or pointer 52". When these parts are actuated from the electromagnet 85, the slide member 88 is moved by the arm 88 inwardly of the opening 8| to place the pin contact 58 in the path of the index-or pointer 52" at the side thereof opposite to that which is opposed by the fixed pin contact 58. To secure the parts in this latter position, an automatic lock means is provided to that end and it is comprised in a lock pin 81 which is mounted for horizontal sliding movements in the post 58 for engagement in a transverse opening 88 in the slide member 88 as required. The outer end of the lock pin 81 is provided with a knob 88 to facilitate its withdrawal for the release of the slide member 88 when necessary, and also with a coiled spring 18 arranged to snap the lock pin into locking position whenever the slide member is moved to place the opening 88 in line therewith.

As is best shown in Figure 6, the electromagnet 85 is preferably provided with a base plate 1| arranged for sliding adjustment on the post base 51. One end of the base plate 1| is pro- Jected outwardly of the electromagnet 85 and is formed with parallel longitudinal slots 12 engaged with securing bolts 13 rising from the post base 51. With nuts on the upper ends of the bolts 18 loosened, the plate 1| is moved relatively to the bolts to selectively position the electromagnet 85 relatively to the armature 88 and is thereafter secured in place by a tightening up of the nuts against the plate 1|.

Pivoted, as at 14, to the side of the post 58 opposite the lock pin 81, is a switch arm 15 which has a contact member 18 at its end above the pivot 1| for cooperation with a fixed contact 11 mounted on the top of the post 58 and a second contact member 18 at its opposite end for cooperation with a contact member 18 projecting sidewise from the rear side of the post 58. This contact member 18 is in connection with the fixed contact pin 58 that is cooperative with the index or pointer 52" of the altimeter 52. The switch arm 15 is normally held in position, that the upper contact member 18 is engaged with the fixed contact 11 and the lower contact member 18 is disengaged from the side contact member 18, by means of a plunger 88 mounted for horizontal sliding movement in the top end of the post 58, one end of the plunger having bearing against the inner side of the switch arm 15 at a point above the pivot 14. The opposite end of the plunger 88 is provided with a knob 8| to facilitate its manipulation, and a coiled spring 82 interposed between the knob and the opposed side of the post 58 and arranged to tension the plunger toward and against the switch arm. Pivoted, as at 83, on the switch arm 12 below the pivot H is a contact member 84 which has a guide pin 85 projecting therefrom and engaged in an opening in the vertical member or post 58. This pin 85 is disposed in line with the lock pin 81 so as to be abutted by the opposed end of the latter when the lock pin 81 is moved into looking engagement with the transverse opening 88 in the slide member 88. Motion of the lock pin 81, under the tension of its spring 18, is transmitted to the pin 88 and the contact member 84, so that the switch arm 15 is swung on its pivot 14 breaking a circuit at the contacts 18 and 11 and closing a circuit at the contacts 18 and 18. From this, it will be obvious that the power of the spring 18 is greater than that of the spring 82, and as the switch arm 15 is swung on its pivot 14 by the motion of the lock pin 81, the plunger 88 is moved against the urge oi the spring 82 to return the switch arm to normal position. Circuit connections 88, 81, 88, 88, and 88, lead from the contacts 58, 18, 11, 18 and 84, respectively for purposes which will be presently explained.

As shown in Figure 15, this switching device is connected in circuit with the electric motor 43 and a suitable current source 8|, as follows: The index or pointer 52'' 01 the altimeter 52 by a conductor 82 to the positive terminal of the current source 8|. The fixed pin contact 58 direct to the contact 18 which is alternately cooperative with the contacts 18 and 84 on the switch arm 15. The contact 18 by connection 81 to the positive side of the current source 8|. The contact 11 by connection 88 to one terminal of the motor 43. The movable contact pin 58 by connection 88 to the first of a bank of relays 83, preferably four in number and separately designated 83a, 83b, 83c, 83d, respectively. The fixed contact pin 58 through the contact 84 and connection 88 to the first of a second bank of relays 84, preferably three in number and separately designated 84a.-

84b, and 84c, respectively. The contact 18 by connection 88 to the first of a third bank of relays 85, preferably four in number and separately designated 85a, 85b, 85c, and 8511, respectively. A conductor 88 leads from the positive side of the current source 8| and is commonly connected by a branch conductor 88 to one contact each of the relays 83a, 83b, and 830, in the bank of relays 83, relays 84a, 84b, and 84c, in the bank of relays 84,and relays 85a, 85b, and 850, of the bank of relays 85. The connections 88, 88, and 88, connect one side of the coils of the relays 83a, 84a, and 85a, respectively, and the corresponding sides of the coils of the relays 83b, 83c, 83d, 84b, 84c, 85b, 85c, and 85d, are connected to the other of the contacts of the relays in their respective banks 83, 84 and 85, while the other sides of the coils of all of the relays are connected to a common return conductor 81 to the negative side of the current source 8|. One contact of the relays 83d is connected by conductor 88 to the negative return conductor 81 and its other contact by a conductor 88 to a lead |88 from the other terminal of the motor 43. The lower contact 18, on the switch arm 15, by way of conductor 88 is also connected by a conductor 88 to one contact of the relay 85d which has its other contact connected by a conductor IM to the lead I88 from the motor 43. A lead I82 connects the first named terminal of the motor 43 to the negative side of the current source 8|. A main current control switch |83 may be provided in the conductor 82, substantially as shown.

From these connections and circuits, it will be evident that the switch arm 15 and the several associated contacts functions to reverse the operative motion of the motor 43 correspondingly with opposite motions or fluctuations of the index 52 of the altimeter 52 between the contact pins 58 and 58, and that the operation of the switch banks or groups 53, 33 and 55, in order to allow for a time interval delay between the operative movements of the switch arm 15, the electric motor 33 and the electromagnet 65, so that the elevators 26 will function emciently and smoothly as required and the craft will not be subject to erratic and violent changes in the vertical avigation thereof.

In the operation of this elevator control mechanism, the altimeter 52 is adjusted in the frame 53 by loosening up on the set screw 53 and turned to bring a predetermined graduation on the dial 52' in registry with the fixed contact pin 53. This setting is selected as representative of the maximum altitude that the air craft is to attain on a given flight. With the altimeter so adjusted, the parts of the switch device are initially positioned, as shown in Figures 4, 5 and 6 for the take-oil of thecraft.

The actuating mechanism for the control of horizontal navigation of the craft during flight from the rudder 21 is, as shown in Figures 1, 8, l0 and 16, comprised in a rudder bar I03 which is centrally pivoted, as at I05, on a transverse reinforcement I56 on the floor of and toward the tail end of the fuselage 2 I. The rudder 21 is sustained at normal flying position by opposed springs I53 which are each connected at one end to the fuselage 2| and at the other end to the rudder bar I63 to one side of the pivot I05. The opposite ends of the bar I03 are connected by wires I51, extending rearwardly outward of the fuselage, to corresponding sides of the rudder 21. A pitman I56 extends forwardly from a pivot connection I55 at one end of the bar I03 and has its other end connected, as at I III, to the adjacent end of a rack bar III. The rack bar III extends forwardly from and in line with the pitman I53 and is supported for reciprocating motion on guide rollers I I2 journaled in a bracket II3 rising from the base of an electric motor II3. A gear III on the shaft of the motor H3 is arranged in mesh with the teeth of the rack bar III for imparting reversed reciprocating motions thereto, as required, the motor being secured in proper position on the floor of the fuselage 2|, after the manner as shown in Figure 1.

A compass control is provided for the motor H3, and, as best shown in Figures 9 and 10, it is comprised in a support I I6 which is suspended in the plane of the longitudinal center of the craft from a bracket II1 secured on the ceiling of the interior of the fuselage 2I forwardly of the motor II3. The suspension means for the support II5 consists of an upper member II8 which is attached at its upper end to the bracket II1 by a longitudinal pivot H5 and at its opposite end to a lower member I by a transverse pivot I2I. The lower end of the member I26 is separately pivoted, as at I 22, to the upper ends of a plurality of arms I23 which are equidistantly spaced about the member I25 and pivoted at their lower ends, as at I23, to uprights I25 issuing from the side edges of the support II6.

A compass casing I26 is positioned upon the support II5 between the uprights I25 and has a removable clamp ring I21 for a dial I25 supported horizontally within the casing I26. Mounted in the dial I26 adjacent its edge and rising therefrom is a pair of speed contact pins I23 and I30 for cooperation with an end of the needle I, the latter having its center pivot provided with an electrical connection I32 and the contact pins with electrical connections I33 and I33 respectively.

As shown in Figure 16, the compass switching device is connected in circuit with the electric motor H3 and the current source 5|, as follows: The connection I32 from the pivot of the compass needle III to the positive terminal of the current source 3i. The contact pin I26 by a conductor I33 to the coil of the first of a bank of relays I35, preferably four in number and designated I350, I35b, I350, and H511. The contact pin I35 by a conductor I33 to the coil of the first of a second bank of relays I36, also and preferably four in number and designated I36a, I36b, I380, and I35d. The other sides of these two coils of the relays I 35a and I36a are commonly connected to a return conductor I31 to the negative terminal of the current source 9i. A conductor I38 leads from the positive terminal of the current source 3i and connects branch conductor I33 and I35. The branch conductor I33 connects one of a pair of switch contacts of the relay i351: and the branch conductor I30 the corresponding contact of the switch of the relay I35a. From the switch contact of the relay I35a, the branch conductor I35 extends to and connects one each of the pairs of switch contacts of the relays I35?) and I35c. Similarly, the branch conductor I35 leads to and connects one each of the pairs of switch contacts of the relays I350 and I35b are connected respectively to one side of each of the coils of the relays i351) and I350. Likewise, the corresponding switch contacts of the relays I360 and I35b are connected respectively to one side of the coils of the relays I361),

and I350. The opposite sides of the coils of the relays I35b and I35b are commonly connected to the return conductor I31 leading to the current source 3|. The opposite sides of the coils of the relays I35c and I35d are, in turn, commonly connected to the return conductor I31 by a conductor I3I, and the same sides of the coils of the relays I360 and I35d to the return conductor I31 by a conductor I32. The remaining contact of the relay I350 is connected to one terminal of the electric motor II3 by a conductor I33 and the same contact of the relay I35c to the other terminal of the motor II 3 by a conductor I33. One of the pair of switch contacts of the relay I35d is connected by a conductor I35 to the terminal of the motor II3 that was previously connected by the conductor I33, and the corresponding contact of the relay I35d is connected by a conductor I36 to the terminal of the motor II3 previously connected by the conductor I33. The remaining switch contact of the relay I35d is connected by a conductor I31 to one side of the coil of the relay I35d and to the return conductor I31 by way of the conductor I3I. Likewise, the remaining switch contact of the relay I35d is connected by a conductor I36 to one side of the coil of this relay and to the return conductor I31 by way of the conductor I32.

Referring now to Figures 1, 13 and 14, an automatic gravity control for the throttle of the fuel intake I35 to the engine 29 is depicted and it is comprised in a weighted arm or pendulum I which is mounted on a transverse pivot I5I carried in a bracket I52 secured in a convenient position at one side of the fuselage 2|. The upper end of the pendulum I50 is pivoted, as at I53, to a pitman I53, which has its other end pivoted, as at I55, to operating arm I56 oi the fuel intake I35. Rising from the top side of the bracket I52 is an upright I51 in which a lock pin I 53 is transversely slidable into and out of the path of the upper end of the pendulum I55. The lock pin I58 is headed, as at I59, at one end and has a coiled spring I88 on its headed end and arranged to tension the pin in place on the bracket I52. The arm I50 swings in the plane of the flight path and when pendant in the vertical holds the throttle at engine speed for craft takeoff and climb. The lock pin 58 functions as a stop to prevent rearward swing of the pendulum I59, but the latter is free for forward swing to increase the opening of the throttle whenever the craft tends to nose downward during flight.

In the operation of an airplane equipped with the automatic controls in accordance with the invention, the craft will be moved to desired position for take-off and sustained against forward movement, until the engine 29 is idled for warming and its lubricating oil is properly circulating, and the altimeter and compass controlled switching devices and the pendulum. throttle control are set to selected positions of predetermined altitude, direction, and speed of flight. When these preliminaries are completed, the sustaining means will be released and the craft will get under weigh for take-off in the set direction of its course of flight. As the craft moves forward for takeoff and begins to nose upward on its climb for altitude, the angular relation of the fuselage 2I and the pendulum 35 changes and the motion resulting therefrom is transmitted through the wires 39 to the elevators 26 which, in this instance, are gradually tilted in a downward direction to normal horizontal flight position as the altitude for which the altimeter 52 is set is being attained. As maximum. altitude is approached and before stalling moment is reached, the index or pointer 52" moves toward and against the fixed contact pin 58 and completes the circuit between the current source 9I and the electromagnet through the relay bank 94. During the approach to maximum altitude, the lift of the craft decreases and it begins to nose over the levelling off, with the result of a gradual change in a reverse direction of the angular relation between the fuselage 2| and the pendulous joystick 35 and return of the elevators 26 to normal positions. At maximum altitude, the control of the elevators 26, to maintain average straight-away flight, is automatically taken over by the altimeter 52, as is obvious. Having reached maximum altitude, the craft, being otherwise properly rigged in accordance with known principles of aircraft construction and design, will be in balance and equilibrium and will continue on level flight without control functions until effective forces act to create a change in altitude.

When the circuit is closed at the fixed contact 58, current from the source 9| is impressed on the motor 43 to cause its rotation in a direction that the rack-bar 45 will actuate the pendulous joystick 35 in direction to pull on the wires 39 to return the elevators 26 to normal. Similarly. closing of the circuit at the movable contact 59 will effect a reversal in current flow through the,

motor 43 and thereby reverse the direction of motion of the latter, with the result that the direction of motion of the rack-bar 45 and the joystick 35 is likewise reversed for actuating the elevators 26 to return them from opposite positions to normal. As before stated, the relays 93, 94, and 95, in circuit with the altimeter switching device and the motor 43 function to retard any undue and sudden angular motions of the elevators.

Upon the energizing of the electromagnet 85,

it will attract an armature 88 and thereby cause it to move the lide member in a direction to place the movable contact pin 59 in the path of the' altimeter index 52" at the side thereof opposite to that opposed to the fixed contact pin 58. As the slide member 68 moves as stated, the transverse opening therein will line up with the lock plunger 61 and be engaged thereby through the action of the spring III, in. which position the parts remain until the normal flight of the craft is terminated. As the plunger 81 engages the opening 58 to lock the slide member 89, it pushes against the guide pin of the contact member 84 and swings the switch-arm 15 on its pivot I4 into the other position of its operation. As the upper end of the switch arm 15 swings to its new position, the plunger 88, which normally holds the arm in its initially set position, is depressed and places the spring 82 under tension that will be available to facilitate the return of the arm to initially set position when the lock pin 81 is'withdrawn to release the slide member 68 for the removal of the movable contact pin 59 again from the path of the index or pointer 52" of the altimeter 52. In this position of the control switch parts, the craft will be set on its normal straightaway flight path and will continue so until adverse air conditions are met up with. The balance or equilibrium of the craft will be automatically maintained by the pendulum controls 39 of the ailerons 23.

In the event that the craft starts to lose altitude, the retrograde movement of the index or pointer 52" of the altimeter 52 coincident therewith will finally result in its abutting the movable contact pin 59, when a circuit will be established between the motor 43 and the current source 9| through the back of relays'93. Here, the motion of the motor 43 through the gear 44 moves the rack bar 45 to swing the pendulum 35 onits pivot 31 in a direction to again tilt the elevators in an upward direction to cause the nose of the craft to lift and bring the craft on its course at proper altitude. However, if the craft tended to climb above predetermined altitude, the index or pointer 52" of the altimeter 52, will again move against the fixed contact pin 58, when the motor 43 will be connected to the current source 9| through the bank of relays and the rack bar 45 will be moved by the motor gear 44 in a direction opposite to that as in the first instance, thus causing movement of the pendulum 35 to tilt the elevators 25 in a. downward direction to depress the nose of the craft.

Similarly, in the event that the craft tends to move off its predetermined flight path, the needle I3I of the compass controlled switch device will move against one or the other of the contact pins I29 and I38 and connect the motor II4 to the current source 9|. If the needle I3I abuts the contact pin I29 a circuit will be completed through the bank of relays I36 to cause the motor II4, through its gear II5, to move the rack bar I II in one direction for the actuation of the rudder 21 in proper direction to bring the craft back on its set course. However, should the needle I3I abut the contact pin I30, a circuit will be completed through the bank of relays I38 to cause the motor I I4, through its gear I I5 to move the rack bar III in a reversed direction for the actuation of the rudder in the opposite direction.

As a protective means to the elevator control mechanism, an independent control means is provided for the motor 43 and it is cooperative with the rack bar 45 to effect a stoppage of the motor 46 at the end of each reversed movement of reciprocation of the rack bar. This control means is in the form of a pair of switch blades III each commonly pivoted. as at I62, with an actuating arm I66 to a bracket plate I64 rising from the motor base 46 in front of the rack bar mechanism on the motor bracket 41. A switch blade I6I and an arm I63 are interconnected by a spring I65 to impart a snap action to the switch blade between spaced stop pins I66, I61, projecting from the bracket plate I64. The free end of the arm at I63 is forked, as at I63, for engagement with a projection I66 on the front side of the. rack bar I46 in the reversed directional motions of the latter, the bracket plate I64 being slotted to permit movement of the projection I66 therein for cooperation with the actuating arms I63. The stop pins I61, at the inner side of each switch blade I6I, are parts of circuit terminal contacts I69, I16, which are to be connected, the contact I66 with one terminal of the motor 43 by a lead "I, and the contact I16 to the other terminal of the motor 43 by a lead I12. Similarly, the pivots I62 are parts of circuit contacts I13, I14, at the outer sides of the switch blades I6I, and these contacts are connected by leads I15, I16, respectively, to the positive and negative sides of the current source.

With both switch blades I6I set to close the circuit on the motor at the contacts I69, I10, the forks I63 of the actuating arms I63 will be positioned against stop pins I11 and in the patch of the projection I66 on the rack bar 45, so that motion of the latter in either of its reversed directions of movement will cause the projection I68 to, engage the longer finger of a fork I63 and move the arm I63 with it until the tension on a spring I 65 acts to snap a switch blade I6I away from either of the contacts I69, I10, depending upon the direction of movement of the rack bar 46. The circuit thus broken is to be restored manually by moving the actuating arm I63 to normal operative position, when the switch blade I6 I will be snapped back into circuit closing position by the spring I66.

This pilotless or robot-controlled aircraft is primarily intended for military purposes and may be provided with usual manual controls (not shown) if desired. In any case, it is to be substantially constructed to fully meet all war-time conditions and requirements and, in the absence of manual controls, it may be built without regard to interior finish and human accommodations and conveniences, in order to minimize cost of manufacture. No provision has been disclosed herein for grounding the craft once it is in flight, since it may be self-destroying upon reaching an objective, as by crashing upon exhausting of its motor fuel supply or being blown to pieces or burned if provided with a suitable timed explosive or inflammable charge (not shown). However, and if desired, the craft may be captured during flight and'for subsequent grounding by the transregularly piloted airplane or other aircraft. To enhance the value of the proposed craft for military purposes, it may be provided with any suitable bomb carrying and discharge means (not shown) whereby the bombs may be dropped upon an objective within a predetermined radius of flight of the craft, which radius may be predetermined by a measured fuel supply up to maximum capacity.

Without further description, it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art, and it will of course be understood that changes in form, proportion and minor details of construction may be resorted to, without departing from the spirit of the invention or its scope as claimed.

Having thus fully described my invention, what I claim is:

1. In an automatic flight control for air craft, an electrical mechanism for actuating each of the elevator and rudder controls for vertical and horizontal avigation respectively of the craft, an automatic switch means for controlling the operation of each electrical means one independently of the other to maintain the craft at a given altitude and direction, and means for preventing the operation of the switch means for the actuation of the electrical mechanism for the elevator controls until the craft has reached a predetermined altitude.

2. The flight control as set forth in claim 1, wherein an electromagnet means is provided to automatically release the said switch means for controlling the operation of the elevator controls when the craft has reached the predetermined altitude.

3. The flight control as set forth in claim 1, wherein an altimeter is provided to control the Operation of the said switch means and certain of the contacts of the switch means are cooperative with the altimeter index for controlling the circuits of the electrical mechanism for the automatic actuation of the elevator controls correspondingly with fluctuations of the index, and the altimeter has means for its adjustment relatively to the contacts to cause the index to cooperate therewith at a selected altitude.

4. The flight control as set forth in claim 1, wherein a lock means is provided to hold the said switch means normally inactive with respect to the operation of the elevator controls by its electrical mechanism during the takeofl and climb of the craft for altitude, and means for automatically releasing the lock means to place the switch means in its operative condition immediately following the arrival of the craft at predetermined ceiling altitude.

5. The flight control as set forth in claim 1, with the automatic switch means provided with a frame for adjustably supporting an altimeter, a fixed contact on the dial of the altimeter for cooperation with the movable altimeter index, a movable contact to be brought into cooperative relation with the fixed contact and the index after a selective setting of the altimeter within the frame, lock means normally holding the movable contact out of such cooperative relation, and means for automatically releasing said lock means upon initial contact of the index with the fixed contact at the moment of maximum flight altitude of the craft.

GIUSEPPE MINELLI. 

